Magnetic tachometer.



. v PATENT-ED DEC. 5, 1905. 5'. H. PORTER & B.'GURRIBR.

MAGNETIC TAGHOMETER.

APPLICATION FILED JUNE 17; 1905.

, INVENTORS. Edwin E'Pw'ter. ,Burle W1 TNESSES:

U I W zyb 62077-067 BY v .- HATTORNEV.

. st'ruQted are -necessari y a "bulky and i To all whorrt t't' rr'zla zjc'or'werru v ,"Befitj known that we, EDWIN H; PORTER and BURLEIGH'GU R ER, citizens of the United States, 'residingat Philadelphia, in the county 5 of' 1?hiladelphia and State of Pennsylvania,

haveinventedcertainnew and useful Improvements infMagneticTachomcters; ofwhich the followingisjaspecification.

Quljinventionj[relates to improvements in m et fiflqbemete s-j Tillie-object of our invention is to produce a magnetic tachometerthat is simple, accurate, n .nermas t yxr lablewhe in i a in t speed of revolving'shaftsto which it may be ppli d, A

Afurtheriobjectj of ourinvention is to produce; a1tnagn i'c tachometer of a size readily carried iufitl il ,ocket, freeo'fromg partsasil'y deranged andhavmg, a permanent magnetic eircuitf'socons'tructed asto ma ntama maximuInYmagI e cfluxthrough an armature for and give .a' maximum, torque to v, rwhenlrfotated at :a given speed; ovide 8t prattically elosedfrnagn'etic circuit, ,not"t"o hejafl'ected by external magnetic field's] also;

ch will'be permanent through timegfinsu'ring permanent ac een v'the i'evolvingf magnets and their drivingjshaft, "thus making the instrument readily da table to use on widely varying as heretofore "con-Q 49 their has, been such that the magiiig eacliother and embracing in ple system-of change-gears and a pointed I SpBcification'of Letters Patent.

.lpplltation'flled Jmiv, 1905. '8erla1No.265,687-- 4 r objectf is tofprovide a int q to provid e the ta:- Yple" arrangement of 'varigive it variable-speed ratio a a v d the b he c r y, rapidly deterioratesandfor theabo've-reasons r they havenotibeen,a'cptnmercial;success. ()nrfin'vention(consists in, a magnetic tal twoipermanent multipolar; ag n tshaving poles of opposite PATENT 1D an, ctr t AND BURLEIGH amm- OF-PHILADELPHIA,

@PENNSYLYANIA. a

,ItlAGN ETI C TAQHoMs ER.

' Patented Dec. :5, 1905.

spindle to engage with the rotating shaft whose speed is to be measured. v Referring to the drawings, Figure 1 is a plan view of our improved tachometer. Fig.

2 is a sectional view on line 2 2, Fig. 1. Fig.

3 is a plan view of the magnet'detached. Fig. 4 isa plan view of the armature detached, and .Fig. 5 is a detached view of the gearcas1ng."-

In the drawings, A is a casing consisting of a base A and the sidewalls A", in whicharesecured the dial-plate A and the glass A for protecting thesame. The'base A has 'a shaft Bmounted therein, having squared ends '6 and Z), adapted to receive the shank C of the spindle C, which is provided with a pointed end 0', adapted to be held in the center mark upon the end', of a'revolving shaft the speed of which is to be indicated. A variable-speed mechanism D is adapted to be interposed between'theispindle 'C"and the shaft'B, which will be more ,fully describedhere'inafter A 1 B,-whic'h drives the bevel gear wheel E, attached tothe sleeve E, carryingthe rotatable magneticistructure F; Said sleeve'is'mountbevel gear-wheel B is mounted upon the shaft ed upon a hollow shaft A'Zprojecting from the base A. Mounted within the hollow shaft A? is a pivotal shaft G, whichrests upona jeweled bearing g, and .its upper portion is guided in a jeweled bearing'g, carried by the dial-plate A Upon the upper-"end of the 8' 1 said pivotal shaft is an indicating pointer G,

which is held in its normal position; as shown in Fig. 1, by a coil-spring G having one end site'end attached to a pos'tGi on the dial-plate A, against the action'of whichspring the intions.

; attached to the pivotal shaft G and its oppo- Y llhe rotatable magnetic structure F i'scon structed in two parts, H and H; ,each'of which is provided with radial polar projections k and k, so arranged as to form an air-gap between their adjacent ends and betweenwhich is sus- I pended. the cylindrical armature I, which is carried upon the pivotal shaft G by arms 43.

The two portions H and H of the rotatable magnetic structure are concentrically 'mount- 1edupon a disk Eicarried by the sleeve E.

The dish E forms a base for the magnetsH- and H, so that the said magnets H and H'- rotate together. The magnets H and H are" made up of hardened steel laminations it as shown in Fig. 2, which are rigidly secured together by pins 72.. The laminations of the.

ture to receive the sleeve E, and from which hub the radial polarprojections 71. extend, while the laminations of the magnet H form an annular yoke from which the radial polar projections I: extend, thus completing a permanent magnetic circuit between the said radial polar projections h and k, as clearly shown ture I is non-magnetic-and is mounted between the poles N and S of the magnets H and H, as above described.

Our invention dependsforits action on the well-known principle of the interaction of electric currents induced in an armature by a rotating field with the field thatinduces them.

By applying the pointcof the spindle C to a revolving shaft the motion will be communicated to the shaft B and through the bevel gear-wheels B and E to the magnetic structure F, thus causing the magnets H and H to revolve, the elfect of which is to give a torque to the armature I and cause the indicator-hand to move over the dial in the direction of the arrow, Fig.' 1, the magnets maintaininga permanent maximum magnetic flux through the armature. The are of travel of the indicatorhand is proportional to the speed at which said magnets are rotated, and as the speed of said magnets corresponds to the speed of the shaft to be indicated the readings may be readily taken from the dial, which is properly calibrated.

It is desirable for wide ranges of speed to increase .or reduce the speed of the tachometer in relation to the speed of the shaft to be indicated. We therefore provide a variablegear mechanism D, which may be interposed between the spindle'C and the shaft B. This mechanism consists of a casing D, in which are mounted shafts D and D carrying differential gear-wheels D and D meshing with each other. The shafts D and D are ,each

' provided with squared ends at one side of the T the dowel-pins (I, so that either the shaft D",

carrying the larger gear-wheel, may be con' nected to the shaft B,or .the shaft D. carrying the smaller gear-wheel, may be attached 4' to the shaft B.- The spindle C may be placed on either shaft Dor D. When in the posi tion shown in full lines, Fig. 2, the speed raecaees tic ishct changed. ,When in thpcsition the larger gear-wheel, D will be the driver, magnet H form a central hub having an aperand the speed ratio will be increased and additional series of calibrations or a constant is provided on the scale for correctly indicating the speed with the different ratio of gears. The casing D may be transferred to the opposite side of casing, so as to.connect the shaft D or D to the opposite end of shaft B, reversing the relative direction of rotation of spindleC and magnets H and H.

Having thus described our invention, we claim and desire to secure by Letters Patent- 1. In a magnetic tachometer, the combination of a permanent magnetic structure consisting of two concentric coaxial members embracing a plurality of permanent magnetic poles, the same connected together and revolubly mounted, a cylindrical metallic conducting-armature'movably mounted between the poles of said magnetic structure, an indieating-pointer and a resisting-spring for said armature, a calibrated scale and means for rotating said magnetic structure, substantially as described.

2'. In a magnetic tachometer, the combination of a permanent magnetic structure consisting of two concentric, coaxial, circular laminated field members of a multipolar type, poles of opposite polarity of each field mem. ber facing each other, the whole revclubly mounted and embracing between opposite poles a cylindrical, metallic, conducting-armature, a resisting-spring for said armature, an indicating-pointer on said armature, a callbrated scale and means for rotating said magnetic structure, substantially as described.

3. In a magnetic tachometer, the combination of two coaxial, concentric laminated, multipolar, permanent magnets, rotatably mounted together on a bearing, said magnets having poles of opposite polarity adjacent each other, a conducting cylindrical armature embraced by said magnets, a suitable pivotal shaft carrying said armature, an indicatingpointe'r a' resisting-spring and a calibrated scale, the whole operatively connected togather, substantially as described.

4. v In a magnetic tachometer, the combination of two permanent magnets of a circular multipolar type, one having outwardly-projecting poles, the other. inwardly-projecting poles, the two magnets concentrically mounted together with opposite poles adjacent, the same arranged to revolve coaxia'lly, a drivingshaft and a detachable gear mechanism for driving said magnets, a conducting cylindrical armature mounted between the les of said magnets on pivots to allow of oscillation, a resisting-spring connected to said armature. .an indicating-pointer carried by said arms ICQ "hire, and a calibrated scale, snbstantiallyas pointer.on said pivotal shaft, a calibrated scale. f

described. v andmeansfor connecting said driving-shaft 5. In a magnetic tachometer, the combinawith a revolving shaft, substantially. as .de- 5 tion ofla casing, abearing having a drivingscribed. I 5 shaft mounted therein, ahollow verti'cal shaft, In testi'mony'whereof weaflix our signatures I %ma%neticst1];uctiuremo(\1n(i1teduponlthg Sill-I156, a "inpre'sence of two witnesses-. eve gear-w ee on sai riving-s a tan on 3 r i said magnetic structure meshing together, a pivotal shaft mounted within said hollow v l' ,m shaft, an armature carried by said pivotal Witnesses:

' shaft and embraced by said magnetic struc-' WM. A. ALLISON,

ture, a"resisting-spring and an indicatingfWM. R; STAGKHOUSE. 

